What Medicine Shrinks the Prostate? Here’s What to Know

Two main types of prescription medicine can shrink an enlarged prostate: 5-alpha reductase inhibitors like finasteride (Proscar) and dutasteride (Avodart), and alpha-blockers like tamsulosin (Flomax) which relax prostate muscles but do not actually shrink the gland. Only the 5-alpha reductase inhibitors have been shown in clinical research to reduce prostate size over time, typically by 20-30 percent within 6 to 12 months. Alpha-blockers relieve symptoms faster but address the muscle tension around the prostate rather than the size of the gland itself. This distinction matters because choosing the right medicine depends on whether your main goal is symptom relief or actually shrinking the tissue.

What Causes an Enlarged Prostate in the First Place?

The medical term is benign prostatic hyperplasia or BPH. It is not cancer and it does not turn into cancer. But it affects roughly half of men in their 50s and up to 90 percent of men by age 80, according to the National Institutes of Health.

Testosterone naturally declines as men age. But a related hormone called dihydrotestosterone or DHT tends to stay high in prostate tissue. DHT tells prostate cells to keep growing. Over years this leads to a gland that is larger than normal and squeezes the urethra. That squeezing causes the classic symptoms: trouble starting urination, weak stream, frequent trips to the bathroom especially at night, and the feeling that the bladder never fully empties.

Genetics play a role too. If your father had BPH your risk is higher. Obesity and lack of exercise also increase the odds. But the core driver is hormonal — specifically DHT acting on prostate cells over decades.

Do 5-Alpha Reductase Inhibitors Actually Shrink the Prostate?

Yes. This is the only class of medicine that has solid evidence for actually reducing prostate volume. Finasteride and dutasteride both block the enzyme that converts testosterone into DHT. Less DHT means less signal for prostate cells to grow. Over time some cells even die off and the gland gets smaller.

Research published in the Journal of Urology found that finasteride reduced prostate volume by roughly 18 percent after one year and up to 27 percent after four years. Dutasteride works similarly and may work slightly faster because it blocks both types of the enzyme. The National Institute of Diabetes and Digestive and Kidney Diseases includes both drugs as first-line treatments for BPH.

These medicines do not work overnight. Most men notice improvement in symptoms after three to six months. Maximum effect takes about a year. That is a long wait for someone who just wants to pee without standing there for 30 seconds before anything comes out.

One more thing: these drugs can lower PSA levels by about 50 percent. That matters because PSA is used to screen for prostate cancer. If you take finasteride or dutasteride your doctor needs to know so they can double your PSA number to get an accurate reading.

What About Alpha-Blockers — Do They Shrink Anything?

No. Alpha-blockers like tamsulosin (Flomax), alfuzosin (Uroxatral), and silodosin (Rapaflo) relax the smooth muscle in the prostate and bladder neck. This opens the urethra and makes urination easier. But these drugs do not reduce prostate size at all.

A study in the New England Journal of Medicine compared tamsulosin to finasteride over one year. Tamsulosin improved symptoms faster — within two to four weeks — but finasteride showed better long-term results for men with larger prostates. Men with a prostate volume over 40 milliliters benefited more from finasteride. Men with smaller prostates did just as well on tamsulosin alone.

So the choice depends on prostate size. If your ultrasound shows a 30 milliliter gland, an alpha-blocker might be all you need. If it shows 60 milliliters, you likely need a 5-alpha reductase inhibitor to actually shrink the thing.

Side effects differ too. Tamsulosin can cause dizziness, stuffy nose, and a condition called retrograde ejaculation where semen goes into the bladder instead of out the urethra. It is not harmful but it can be alarming if you do not expect it. Finasteride and dutasteride can cause decreased libido, erectile dysfunction, and breast tenderness in some men.

Can Combination Therapy Work Better Than One Medicine Alone?

Yes, and the evidence is clear. The Medical Therapy of Prostatic Symptoms study, funded by the National Institutes of Health, followed over 3,000 men for more than four years. It found that taking both finasteride and an alpha-blocker worked better than either drug alone for preventing BPH progression.

Men on combination therapy had a 66 percent lower risk of developing acute urinary retention — meaning they could not pee at all and needed a catheter. They also needed surgery less often. The downside is more side effects. You get the potential side effects from both drugs at once.

Doctors typically start with one drug. If symptoms are not controlled after a few months they add the second. Some men do well on a single drug and never need the other. There is no rule that everyone needs both.

What About Natural Supplements That Claim to Shrink the Prostate?

This is where the noise gets loud. Saw palmetto, beta-sitosterol, pygeum, and stinging nettle are widely sold as natural prostate remedies. The marketing often says they shrink the prostate or work like prescription drugs. The evidence does not back that up.

The largest and most rigorous study on saw palmetto was published in the Journal of the American Medical Association in 2011. It gave men either a high-dose saw palmetto extract or a placebo for 72 weeks. The result: no difference in symptom scores, prostate size, or urine flow. None. That does not mean saw palmetto is useless for everyone. Some people report feeling better on it. But if your goal is measurable shrinkage of the gland, the data says no.

Beta-sitosterol has some small studies suggesting it improves symptom scores. But those studies did not measure prostate size. So it might help how you feel without actually changing the anatomy. Pygeum and stinging nettle have even weaker evidence. As of 2026 there is no clinical evidence from large, well-controlled trials that any herbal supplement shrinks the prostate in a meaningful way.

If you want to try a supplement anyway, talk to your doctor. Some supplements interact with prescription drugs. And be skeptical of any product that promises to shrink your prostate in a few weeks. That claim alone tells you the company is not being straight with you.

What Lifestyle Changes Actually Help?

Medicine is not the only option. Some lifestyle changes can reduce symptoms even if they do not shrink the gland much. The evidence here is moderate but worth knowing.

Exercise helps. A study in Medicine and Science in Sports and Exercise found that men who walked regularly had lower BPH symptom scores. The theory is that exercise reduces inflammation and improves blood flow to the pelvic area. Even 30 minutes of walking five days a week made a difference.

Diet matters too. A diet high in red meat and processed foods is linked to worse BPH symptoms. A diet rich in vegetables, fruits, and healthy fats is linked to milder symptoms. Some research points to zinc from pumpkin seeds and oysters as possibly helpful. The evidence is not strong enough to call it a treatment but it is reasonable to eat well anyway.

What to avoid: drinking large amounts of fluid before bed, caffeine, alcohol, and decongestants like pseudoephedrine. These can all make symptoms worse. If you are waking up three times a night to pee, try cutting fluids after 7 PM and see what happens.

When Should Someone Consider Surgery Instead of Medicine?

Surgery is not the first option. But it becomes the right choice in certain situations. If medicine does not control symptoms after six to twelve months, surgery is worth discussing. If you have had acute urinary retention — meaning you could not pee at all — the risk of it happening again is high enough that surgery is often recommended.

Other reasons: blood in the urine from BPH, bladder stones, kidney damage from chronic obstruction, or simply being tired of peeing all night and not wanting to take pills forever.

The most common surgery now is transurethral resection of the prostate or TURP. It is not a full removal. The surgeon goes through the urethra with a scope and trims away excess prostate tissue. Recovery takes a few weeks. Most men get significant symptom relief. Newer options like laser treatments and water vapor therapy (Rezum) have less downtime and fewer sexual side effects but may not work as well for very large prostates.

Surgery is not risk-free. Possible complications include bleeding, infection, erectile dysfunction, and retrograde ejaculation. But for men with severe BPH, the quality of life improvement often outweighs the risks.